Drilling and excavation is widely practiced for various purposes such as drilling for tunnels, mines and drilling shafts for oil and gas exploration. With new technologies enabling horizontal and vertical drilling deep into layers of earth strata, the drilling, which requires large amounts of water, often generates large volumes of excavated slurry of suspended solids that requires costly removal and disposal. This presents a logistic and environmental problem that is costly to solve.
The current practice of material handling depends on the type of hole being drilled (e.g., well, mine shaft, or tunnel), the site conditions and the size, orientation, and length of the hole. In general, materials must be transported from the bit face of drilling to the surface and from the surface to the land field for disposal. Material handling logistics limit the advance of hole-boring when materials cannot be transported to the surface as rapidly as they are mined or when they cannot be moved from the surface to a disposal area as rapidly as they are brought to the surface. Surface disposal problems often create environmental problems associated with toxic materials that maybe liquids or solids.
The amount of slurry created in the bit phase of tunneling is four times the quantity of slurry generated in the vertical drilling phase. In drilling, the materials may not fit in the annular space between the hole and the drill pipe. Modern tunnel excavation technologies use water in copious amounts to cool the excavation equipment.
The excavated solids from both vertical and horizontal usually contains suspended, silt, sand, cement, clay, and bentonite. These solids mixed with water are generally considered difficult to treat because of their high abrasiveness, viscosity and density and therefore the need to separate the water from the sludge. Concentrating the sludge makes it more feasible and less expensive to transport for disposal or recycle for further processing. The water removed from the excavated sludge may be reused for drilling or drinking.